Sleep Disorders

SLEEP DISORDERS

Disorders of sleep are among the most common problems seen by clinicians.

More than one-half of adults experience at least occasional insomnia,and 15–

20% have a chronic sleep disturbance.

Approach to the Patient

Pts may complain of (1) difficulty in initiating and maintaining sleep (insomnia);

(2) excessive daytime sleepiness,fatigue, or tiredness; (3) behavioral phenomena

occurring during sleep [sleepwalking,rapid eye movement (REM) behavioral

disorder,periodic leg movements of sleep,etc.]; or (4) circadian rhythm

disorders associated with jet lag,shift work,and delayed sleep phase syndrome.

A careful history of sleep habits and reports from the sleep partner (e.g.,heavy

snoring,falling asleep while driving) are a cornerstone of diagnosis. Completion

of a day-by-day sleep-work-drug log for at least 2 weeks is often helpful. Work

and sleep times (including daytime naps and nocturnal awakenings) as well as

drug and alcohol use,including caffeine and hypnotics, should be noted each

day. Objective sleep laboratory recording is necessary to evaluate sleep apnea,

narcolepsy,REM behavior disorder, periodic leg movements, and other suspected

disorders.

Insomnia

Insomnia,or the complaint of inadequate sleep,may be subdivided into difficulty

falling asleep (sleep-onset insomnia),frequent or sustained awakenings

(sleep-offset insomnia),or persistent sleepiness despite sleep of adequate duration

(nonrestorative sleep). An insomnia complaint lasting one to several

nights is termed transient insomnia and is typically due to situational stress or

a change in sleep schedule or environment (e.g.,jet lag). Short-term insomnia

lasts from a few days up to 3 weeks; it is often associated with more protracted stress such as recovery from surgery or short-term illness. Long-term (chronic)

insomnia lasts for months or years and,in contrast to short-term insomnia,

requires a thorough evaluation for underlying causes. Chronic insomnia is often

a waxing and waning disorder,with spontaneous or stressor-induced exacerbations.

EXTRINSIC INSOMNIA Transient situational insomnia can occur after

a change in the sleeping environment (e.g.,in an unfamiliar hotel or hospital

bed) or before or after a significant life event or anxiety-provoking situation.

Treatment is symptomatic,with intermittent use of hypnotics and resolution of

the underlying stress. Inadequate sleep hygiene is characterized by a behavior

pattern prior to sleep and/or a bedroom environment that is not conducive to

sleep. In preference to hypnotic medications,the pt should attempt to avoid

stressful activities before bed,reserve the bedroom environment for sleeping,

and maintain regular rising times.

PSYCHOPHYSIOLOGIC INSOMNIA Pts with this behavioral disorder

are preoccupied with a perceived inability to sleep adequately at night.

Rigorous attention should be paid to sleep hygiene and correction of counterproductive, arousing behaviors before bedtime. Behavioral therapies are the

treatment of choice.

DRUGS AND MEDICATIONS Caffeine is probably the most common

pharmacologic cause of insomnia. Alcohol and nicotine can also interfere with

sleep,despite the fact that many pts use these agents to relax and promote sleep.

A number of prescribed medications,including antidepressants, sympathomimetics,

and glucocorticoids,can produce insomnia. In addition, severe rebound

insomnia can result from the acute withdrawal of hypnotics,especially following

use of high doses of benzodiazepines with a short half-life. For this reason,

hypnotic doses should be low to moderate,the total duration of hypnotic therapy

should be limited to 2–3 weeks,and prolonged drug tapering is encouraged.

MOVEMENT DISORDERS Pts with restless legs syndrome complain

of creeping dysesthesia deep within the calves or feet associated with an irresistible

urge to move the affected limbs; symptoms are typically worse at night.

Treatment is with dopaminergic drugs (pramipexole 0.25 to 1.0 mg daily at 8

P.M.. or ropinirole 0.5 to 4.0 mg daily at 8 P.M.). Periodic limb movement

disorder consists of stereotyped extensions of the great toe and dorsiflexion of

the foot recurring every 20–40 s during non-rapid eye movement sleep. This

common condition is present in 1% of the population; treatment options include

dopaminergic medications or benzodiazepines.

OTHER NEUROLOGIC DISORDERS A variety of neurologic disorders

produce sleep disruption through both indirect,nonspecific mechanisms

(e.g.,neck or back pain) or by impairment of central neural structures involved

in the generation and control of sleep itself. Common disorders to consider

include dementia from any cause, epilepsy, Parkinson’s disease,and migraine.

PSYCHIATRIC DISORDERS Approximately 80% of pts with mental

disorders complain of impaired sleep. The underlying diagnosis may be depression, mania,an anxiety disorder,or schizophrenia.

MEDICAL DISORDERS In asthma,daily variation in airway resistance

results in marked increases in asthmatic symptoms at night,especially during

sleep. Treatment of asthma with theophylline-based compounds,adrenergic agonists, or glucocorticoids can independently disrupt sleep. Inhaled glucocorticoids that do not disrupt sleep may provide a useful alternative to oral drugs.

Cardiac ischemia is also associated with sleep disruption; the ischemia itself may result from increases in sympathetic tone as a result of sleep apnea. Pts

may present with complaints of nightmares or vivid dreams. Paroxysmal nocturnal

dyspnea can also occur from cardiac ischemia that causes pulmonary

congestion exacerbated by the recumbent posture. Chronic obstructive pulmonary

disease, hyperthyroidism, menopause,and gastroesophageal reflux are other causes.

TREATMENT

Insomnia without Identifiable Cause Primary insomnia is a diagnosis

of exclusion. Treatment is directed toward behavior therapies for anxiety and

negative conditioning,pharmacotherapy for mood/anxiety disorders, an emphasis

on good sleep hygiene,and intermittent hypnotics for exacerbations of

insomnia. Cognitive therapy emphasizes understanding the nature of normal

sleep, the circadian rhythm,the use of light therapy,and visual imagery to

block unwanted thought intrusions. Behavioral modification involves bedtime

restriction,set schedules, and careful sleep environment practices. Judicious

use of benzodiazepine receptor agonists with short half-lives can be effective;

options include zaleplon (5–20 mg),zolpidem (5–10 mg),or triazolam

(0.125–0.25 mg). Limit use to 2–4 weeks maximum for acute insomnia or

intermittent use for chronic. Some pts benefit from low-dose sedating antidepressants

(e.g.,trazodone,25 –100 mg).

Hypersomnias (Disorders of Excessive Daytime Sleepiness)

Differentiation of sleepiness from subjective complaints of fatigue may be difficult.

Quantification of daytime sleepiness can be performed in a sleep laboratory

using a multiple sleep latency test (MSLT),the repeated daytime measurement

of sleep latency under standardized conditions. Common causes are

summarized in Table 43-1.

SLEEP APNEA SYNDROMES Respiratory dysfunction during sleep is

a common cause of excessive daytime sleepiness and/or disturbed nocturnal

sleep,affecting an estimated 2 to 5 million individuals in the U.S. Episodes

may be due to occlusion of the airway (obstructive sleep apnea),absence of

respiratory effort (central sleep apnea),or a combination of these factors (mixed

sleep apnea). Obstruction is exacerbated by obesity,supine posture,sedatives

(especially alcohol),nasal obstruction, and hypothyroidism. Sleep apnea is particularly prevalent in overweight men and in the elderly and is often undiagnosed.

Treatment consists of correction of the above factors,positive airway

pressure devices,oral appliances, and sometimes surgery (see Chap 137).

NARCOLEPSY (Table 43-2) A disorder of excessive daytime sleepiness

and intrusion of REM-related sleep phenomena into wakefulness (cataplexy,

hypnagogic hallucinations, and sleep paralysis). Cataplexy, the abrupt

loss of muscle tone in arms, legs,or face,is precipitated by emotional stimuli

such as laughter or sadness. The excessive daytime sleepiness usually appears

in adolescence,and the other phenomena,variably, later in life. The prevalence

is 1 in 4000. Hypothalamic neurons containing the neuropeptide orexin (hypocretin) regulate the sleep/wake cycle and have been implicated in narcolepsy.

Sleep studies confirm a short daytime sleep latency and a rapid transition to

REM sleep.

TREATMENT

Somnolence is treated with modafinil,a novel wake-promoting agent; the

usual dose is 200–400 mg/d given as a single dose. Older stimulants such as methylphenidate (10 mg bid–20 mg qid); pemoline,dextroamphetamine, and

methamphetamine are alternatives,particularly in refractory pts. Adequate

nocturnal sleep time and the use of short naps are other useful measures.

Cataplexy,hypnagogic hallucinations, and sleep paralysis respond to the

tricyclic antidepressants protriptyline (10–40 mg/d) and clomipramine

(25–50 mg/d) and to the selective serotonin uptake inhibitor fluoxetine

(10–20 mg/d).

Disorders of Circadian Rhythmicity

Insomnia or hypersomnia may occur in disorders of sleep timing rather than

sleep generation. Such conditions may be (1) organic—due to a defect in the

hypothalamic circadian pacemaker,or (2) environmental—due to a disruption

of entraining stimuli (light/dark cycle). Examples of the latter include jet-lag

syndrome and shift work. Delayed sleep phase syndrome is characterized by

late sleep onset and awakening with otherwise normal sleep architecture. Brightlight phototherapy in the morning hours or melatonin therapy during the evening hours may be effective. Advanced sleep phase syndrome moves sleep onset to the early evening hours with early morning awakening. These pts may benefit from bright light phototherapy during the evening hours.